# POST /api/v2/furlough-balance-mutations

Create a furlough balance mutation

- MCP id: furlough-balance-mutations.store
- Scope: api:write:furlough
- Permission: furlough::create_for_yourself
- Rate cost: 1 unit, write bucket. A write costs the same whatever `view` you ask for.
- Cache-Control: private, no-store

Creates one mutation for the authenticated user and returns it with a `Location` header.

`user_id` is always the caller: this resource carries no on-behalf-of field, so a manager cannot post a mutation for another employee through the API even though the balance screen in plnnrly can. A negative `minutes` is a leave request over the period; a positive `minutes` grants balance and requires `furlough::manage`. `is_approved` is not accepted: the mutation is always the caller's own, so every mutation is created pending and is approved or denied by someone else through PATCH. A special-leave request that would take the special-leave balance for the year below zero is rejected with `422`. Creating a pending mutation notifies every `furlough::manage` holder by e-mail.

## Parameters
- view (string, optional): Which field set to render.
- X-Request-Id (header, optional): A correlation id of your own. It is recorded in our logs next to the server's request id but never returned: the response header always carries the server's id. A value that does not match the pattern is discarded silently, never rejected.
- Idempotency-Key (header, optional): A caller-chosen key that makes this POST safe to retry. Replaying it returns the original response with Idempotency-Replayed: true.

## Request body
- year (integer 1970 to 2200, required): The balance year this mutation counts against. It is not derived from `start`: every balance sum counts by this year, so a mutation whose period moves into another year keeps counting against the year sent here until `year` is sent too.
- minutes (integer, required): The signed balance delta in minutes. Negative consumes balance (a leave request); positive grants it (a manager's adjustment, which requires the `furlough::manage` permission to write). The API never computes this from the employee's working week or the organisation's free days: send the exact number of minutes you mean. A positive value grants balance and requires the `furlough::manage` permission; a caller with only `furlough::create_for_yourself` may write a negative value (a leave request) or zero. On a `special` mutation, the resulting special-leave balance for the year may not go negative.
- start (timestamp (YYYY-MM-DDThh:mm:ssZ), required): Start of the period this mutation covers, in UTC. Equal to `end` on a manual balance adjustment, which covers no period at all.
- end (timestamp (YYYY-MM-DDThh:mm:ssZ), required): End of the period this mutation covers, in UTC. Never before `start`, and equal to it on a manual balance adjustment. Must be on or after start.
- description (string, required): The employee's or manager's own words for this mutation: the reason for the leave, or what the adjustment is for. The only field `?q=` searches.
- type (string, optional): Which leave balance this mutation moves. Regular and special leave are separate balances and never offset one another.

Unknown keys are refused with `422` validation-failed, naming the key.

## Response 201
- id (integer, required): Unique identifier.
- user_id (integer, required, server-assigned): The employee this mutation belongs to. Always the authenticated user on create and not writable.
- acceptor_id (integer or null, required, server-assigned): The user who approved this mutation, set by the server when the mutation resolves to approved. Null while it is pending, and left `null` by a denial. Resolve the name through `GET /api/v2/users/{user}`.
- year (integer, required): The balance year this mutation counts against. It is not derived from `start`: every balance sum counts by this year, so a mutation whose period moves into another year keeps counting against the year sent here until `year` is sent too.
- type (string, required): Which leave balance this mutation moves. Regular and special leave are separate balances and never offset one another.
- minutes (integer, required): The signed balance delta in minutes. Negative consumes balance (a leave request); positive grants it (a manager's adjustment, which requires the `furlough::manage` permission to write). The API never computes this from the employee's working week or the organisation's free days: send the exact number of minutes you mean.
- start (timestamp (YYYY-MM-DDThh:mm:ssZ), required): Start of the period this mutation covers, in UTC. Equal to `end` on a manual balance adjustment, which covers no period at all.
- end (timestamp (YYYY-MM-DDThh:mm:ssZ), required): End of the period this mutation covers, in UTC. Never before `start`, and equal to it on a manual balance adjustment.
- description (string, required, multiline): The employee's or manager's own words for this mutation: the reason for the leave, or what the adjustment is for. The only field `?q=` searches.
- is_approved (boolean or null, required): Approval state, in three values: `null` means pending approval, `true` approved, `false` denied. The balance counts pending and approved mutations alike and ignores denied ones. Writing this field at all requires the `furlough::manage` permission.
- user (Ref or UserSummary, required): The employee this mutation belongs to. Expanding it with `?include=user` additionally requires the `users::read` permission and a token scope covering the users prefix.
- created_at (timestamp (YYYY-MM-DDThh:mm:ssZ), required): Creation timestamp.
- updated_at (timestamp (YYYY-MM-DDThh:mm:ssZ), required): Last-write timestamp; use for incremental sync.
- links (FurloughBalanceMutationLinks, required)
  - self (url, required): The canonical URI of this record.

## Errors
- 403 forbidden-by-policy | insufficient-permission | insufficient-token-scope: Forbidden.
- 409 idempotency-key-in-flight | idempotency-key-reused: Conflict.
- 415 unsupported-media-type: Unsupported media type.
- 422 unprocessable-relationship | validation-failed: Unprocessable content.
- 400 idempotency-key-required | invalid-cursor | invalid-query-parameter | malformed-request | unsupported-parameter: Bad request.
- 401 token-expired | unauthenticated: Unauthenticated.
- 404 endpoint-not-found | resource-not-found: Not found.
- 406 not-acceptable: Not acceptable.
- 429 rate-limit-exceeded: Too many requests.
- 500 internal-error: Server error.
- 503 tenant-unavailable: Service unavailable.

## Example
```bash
curl -X POST \
  'https://<your-url>/api/v2/furlough-balance-mutations' \
  -H 'Authorization: Bearer <token>' \
  -H 'Accept: application/json' \
  -H 'Content-Type: application/json' \
  -H 'Idempotency-Key: <key>' \
  -d '{
    "year": 2026,
    "minutes": -960,
    "start": "2026-07-06T00:00:00Z",
    "end": "2026-07-07T23:59:59Z",
    "description": "Long weekend"
  }'
```